The invention relates to a method and apparatus for the combustion of a mixture of a gaseous or liquid fuel with an oxidising agent. An apparatus, such as a boiler, containing a charge of a radiation substance is provided for a flameless non-catalytic combustion of said mixture. The invention is primarily intended for use in connection with an apparatus, e.g. a boiler, in which the heat produced by this type of combustion is transferred primarily by radiation to heat exchange surfaces, and from there the heat is transmitted to the medium to be heated, said medium being in direct contact with said heat exchange surfaces.
The method and apparatus according to the invention are primarily intended to be used for the heating of liquids, but if suitably constructed, may also be used for the heating of gases.